Dimetrodon
Early - Middle Permian |Image file = Dimetrodon eating.jpg |Image size = 250px |Row 1 title = Kingdom |Row 1 info = Animalia |Row 2 title = Phylum |Row 2 info = Chordata |Row 3 title = Superclass |Row 3 info = Tetrapoda |Row 4 title = Class |Row 4 info = Synapsida |Row 5 title = Order |Row 5 info = Pelycosauria |Row 6 title = Suborder |Row 6 info = Eupelycosauria |Row 7 title = Family |Row 7 info = Sphenacodontidae |Row 8 title = Genus |Row 8 info = Dimetrodon Cope, 1878 |Row 9 title = Species |Row 9 info = D. angelensis Olson, 1962 D. booneorum Romer, 1937 D. giganhomogenes Case, 1907 D. grandis Case, 1907 D. limbatus Cope, 1877 D. lomisi Romer, 1937 D. macrospondylus Cope, 1884 D. milleri Romer, 1937 D. natalis Cope, 1877 D. occidentalis Berman,1977 }} Dimetrodon (meaning "two measures of teeth") was a predatory synasid ('mammal-like reptile') genus that flourished during the Permian Period, living between 280-265 million years ago. Dimetrodon was not a dinosaur, despite being popularity grouped with them. Rather, it is classified as a pelycosaur. Fossils of Dimetrodon have been found in North America and Europe, as well as significant discovery of Dimetrodon footprints in southern New Mexico by Jerry McDonald. Description Dimetrodon was an apex predator, among the largest of its day. It grew to up to 3½ meters (11 feet) in length. The name Dimetrodon means 'two measures of teeth', so named beacuse it had a large skull with two different types of teeth {shearing teeth and sharp canine teeth), unlike reptiles. Dentition showing this differentiation of teeth is called heterodonty. It walked on four side-sprawling legs and had a large tail. Dimetrodon may have moved in a manner similar to present-day lizards. Sail The most distinctive characteristic of Dimetrodon was the spectacular sail on its back (other pelycosaurs such as Edaphosaurus, Ianthasaurus, and Sphenacodon also have this trait). The sail, which was dense with blood vessels, was probably used to regulate body temperature; the surface area would allow it to warm up or cool off more efficntly. This adaption was important because it would give the animal more time to hunt prey. The sail may also have been used in mating rituals and to warn off other predators. The sail was supported by neural spines, each one sprouting from an individual vertebra. Bramwell and Fellget (1973) calculate that a 200kg Dimetrodon would heat up from 26° C to 32° 205 minutes without a sail and in only 80 minutes with a sail.Bramwell, C.D.; Fellget, P.P. (1973). "Thermal regulation in sail lizards". Nature 242: 203-205. doi:10.1038/242203a0 Relationship with Modern Mammals As a synapsid, Dimetrodon was distantly related to modern mammals. Synapsids were the first tetrapods to evolve differentiated (or herodont) teeth. Whereas reptiles hardly ever chew their food, simply gulping it down, synapsids like Dimetrodon developed teeth to help shear meat into smaller pieces for easier ingestion. These 'two-measure teeth' eventually gave rise to the various kinds of teeth present in modern mammals. In Popular Culture In many popular culture references, Dimetrodon is often erroneously seen as a dinosaur or as living a longside dinosaurs. A composite of Edaphosaurus and Dimetrodon fossilsBoth came from Permian strata in Texas. went on display in 1907 in the American Museum of Natural History, New York, presented by the curator of vertebrate palentology Henry Fairland Osborn and illustrated in the pages of Scientific American (May 1907) as "Naosaurus", by the great scientific illustrator Charles R. Knight. References Category:Walking with Monsters Animals